I've got both. I prefer the M69 - it has become my favorite revolver - I shoot it two or three times a week. Personally, I find the recoil of the M69 less than the 3" M629. Here are some chrono results accumulated over time.
Chronoed these from the 2.75” M69. Three rounds at 5 Long paces from muzzle and 68 deg F. Larger sample could change the results a bit. Largest ES was 42 fps. All in new Starline cases and CCI 350 primers.
225gr Barnes XFB with 18.1 gr A#9 avg (1,214 fps (muzzle vel from Labradar)
240gr Cutting Edge Flat Point Mono – 22.6 H110 1,218 fps (1,247 fr 2.5” 329 Alaska Backpacker) Muzzle vel from Labradar
240gr Zero JSP with 24.0gr H110 avg 1,126 fps
240gr JHP Fed Factory avg 1,125 fps (bought at an estate sale “44a 1981 production” – 1,375 fps from 7 ½” RSBH)
260gr WFNGC w/23.0gr H110 avg 1,125 fps
265gr CSWCGC (Lyman Thompson) with 17.5gr A2400 (Deep Seat – crimped over front drive band) 1,119 fps avg
265gr SWCGC (429244) 23.5gr H110, seated and crimped in crimp grove in Mag cases ---------- 1,162 fps
310gr FNGCDC (Lee) with 20.0gr H110 avg 1,100 fps
325gr WLNGC (BTB) with 22.0gr H110 avg 1,104 fps
The 4 ¼” gun gives 40 to 100 fps additional velocity.
I Was curious, so I bought some 305gr Buffalo Bore and Underwood ammo – here are chrono results.
Buffalo Bore, 305 LBT LFN HC rated 1,325 fps
Underwood, 305 LFNGC Plated (HiTech?) rated 1,325 fps
LabRadar muzzle velocity at 33 deg F
S&W M69 2.75" ===> BB 1,195 fps ===> Under 1,147fps
S&W M69 4.25" ===> BB 1,276 fps ===> Under 1,248 fps
Ruger SRH 7.5" ===> BB 1,395 fps ===> Under 1,315 fps
My short M69:
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And the 629
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For practice:
240/265gr Cast over 17.5gr of A2400 deep seated and crimped over front drive band in .44 mag cases
.................. 240/265gr Cast over 6.5gr of HP38/W231 deep seated and crimped over front drive band in .44 mag cases for 880 fps in 4 1/4" gun
.................. 240/265gr Cast over 5.gr of WST (Win Super Target) deep seated and crimped over front drive band in .44 mag cases for 700 fps in 2 3/4" gun
FWIW